Heads on Port side significally Hotter

[bennysku]

I have a 140hp evinrude and the 2 cylinders on the port side are heating up a lot faster than the 2 on the starboard. I have checked all hoses for leaks, replaced thermostat, relief valves, springs, gaskets......no change. Then I replaced the water deflectors under the heads.......no change. While i had the heads off I had the earmuffs on and both sides are getting equal water. I have not ran it so hot the heat alarm goes off, but by touch of hand, you can tell a huge difference. I'm running for about 3-5mins on earmuffs when testing.

So now I wonder, maybe port side is the correct temp, and sb side is running tooo cool????

 

[bennysku]

Re: Heads on Port side significally Hotter

1977 140hp evinrude

 

[CharlieB]

Re: Heads on Port side significally Hotter

You have already addressed all the common causes.

If a water outlet in the adapter plate is clogged with mud, sand or debris, restricting water OUTFLOW into the exhaust, then that side of the engine will heat.

I hope one of the other guys chimes in with an easier fix, otherwise I think lifting the engine off the midsection is going to be necessary.

 

[CharlieB]

Re: Heads on Port side significally Hotter

You are only running this on the hose?

Spark test, ensure that it is running on all 4 and not just on the heated side. That WILL cause one side to be noticably hotter.

 

[bennysku]

Re: Heads on Port side significally Hotter

For good measure I did float it the other day and had the same result. I will check for spark on the starboard side.....that could explain that side being cooler.

 

[emdsapmgr]

Re: Heads on Port side significally Hotter

The valve body in the thermostat housing has two small pinholes in it, one for each side. If these pinholes plug with debris (a common problem) the engine will overheat on that side at idle. They let hot water leak to the back side of the thermostat to heat it up to open at idle. Did you check them when you had the thermo housing apart?

 

[ezeke]

Re: Heads on Port side significally Hotter

While you are checking the pinholes, you might want to check the temperature ratings on your thermostats. They should both have 143 stamped at or near the tip.